Referring to FIG. 1, a panel structure of a conventional display device is illustrated. The display device can be a liquid crystal display (LCD) device. The panel structure of the display device at least comprises a plurality of control wires 11, a plurality of fan-out wires 12, and a pin pad area 13. The plurality of control wires 11 are a parallel arrangement and are connected to a plurality of thin film transistors. The plurality of fan-out wires 12 is connected to the plurality of control wires 11 and the pad of the pin pad area 13. The pin pad area 13 is used to set on control integrated circuits, hence control signals sent by the control ICs are transmitted to the plurality of thin film transistors via the plurality of control wires 11 and the plurality of fan-out wires 12. Moreover, areas of the plurality of control wires 11 are greater than the pin pad area 13. The plurality of fan-out wires 12 are then formed a fan-shaped. A length of the most outer fan-out wire 121 is greater than a length of a middle fan-out wire 122. Therefore, a resistance of the most outer fan-out wire 121 is greater than a resistance of the middle fan-out wire 122, thereby generating a postponement difference when the control signal is transmitted to the thin film transistor. A mura, vertical band (V-band), and horizontal band (H-band) are generated from the images that seriously influence the display quality.
Referring to FIG. 2, another panel structure of a conventional display device is illustrated. The panel structure of the conventional display device is used to overcome shortcomings in FIG. 1. A width of the plurality of fan-out wires 21 is different. The width of the fan-out wires 21 which are near an outside is wider in order to reduce a resistance. On the other hand, the width of the fan-out wires 21 which are near middle is narrower in order to increase a resistance. The modulation is that the resistances of the plurality of the fan-out wires 21 tend toward consistency. However, the wire width is not controlled easily while is etching that cannot reach an expectation. The shape of the fan-out wire 21 can be changed so as to form a non-straight-line, such as fan-out wires 22, 23, and 24. By the fan-out wires 22, 23, and 24, the lengths of the fan-out wires 22, 23, and 24 tend toward consistency, in another word; resistances tend toward consistency. The forms of the fan-out wires 22, 23, and 24 are arbitrary shapes, thereby causing a difficult design. Areas are also too big that cannot reach the expectation as well.
Referring to FIG. 3, a third panel structure of a conventional display device is illustrated and is also used to overcome shortcomings in FIG. 1. A plurality of fan-out wires 31 comprise a first metal layer 311 and a second metal layer 312. A resistance of the first metal layer 311 and a resistance of the second metal layer 312 are different. A length ratio of the first metal layer 311 and a length ratio of the second metal layer 312 contained in the plurality of fan-out wires 31 are modulated, so that resistances of the plurality of fan-out wires tend toward consistency. Referring to FIG. 4, a sectional drawing of a conventional fan-out wire according to FIG. 3 is illustrated. The fan-out wire is formed on a panel 41 and is electrically connected to a control wire 42 and a pin pad 43. The first metal layer 311 and the second metal layer 312 are at the same height and are electrically connected to form a series structure. When the size of the display device is toward large-scale, an outer length of the fan-out wire is different from a middle length of the fan-out wire. In a conventional way, the first metal layer 311 and the second metal layer 312 are used to be the series connection for modulating length ratios, resistances of the plurality of fan-out wires 31 may not tend toward consistency. Consequently, the display quality is further decreased.
Referring to FIG. 5, another sectional drawing of a conventional fan-out wire structure is illustrated. The fan-out wire structure comprises a first metal layer 51 and a second metal layer 52. A material of the first metal layer 51 is different from a material of the second metal layer 52. The fan-out wire structure is formed on the panel 41 of the display device and is electrically connected to the control wire 42 and the pin pad 43. The second metal layer 52 is formed on the first metal layer 51. The second metal layer 52 is electrically connected to the first metal layer 51. Therefore, the second metal layer 52 is formed on a portion of the first metal layer 51. The second metal layer 52 is electrically conducted to the first metal layer 51. A resistance of the first metal layer 51 and a resistance of the second metal layer 52 are modulated when the length 521 of the second metal layer 52 is modulated. The resistances of the fan-out wire structure may not satisfy the modulation requirement from above conventional examples.
Accordingly, a solution must be provided to overcome the drawbacks and disadvantages in order to improve display quality by providing a fan-out wire structure.